Header duct with outlet for cellular flooring



July 14, 1959 F. J. KENNEDY 2,894,534

HEADER DUCT WITH OUTLET FOR CELLULAR FLOORING Filed March 4, 1954 (X INVHVTOR. YQSW United States Patent Oiitice 2,894,534 Patented July 14, 1959 HEADER DUCT WITH OUTLET FOR CELLULAR FLOORING Frank J. Kennedy, Mollint Lebanon, Pa., assignor, by mesne assignments, to H. K. Porter Company, Inc., Pittsburgh, Pa., a corporation of Delaware Application March 4, 1954, Serial No. 414,139 4 Claims. (Cl. 13S-48) This invention relates to ducts for carrying electric wiring in the floors of buildings and for similar uses.

With cellular flooring, crossover ducts are used and these ducts are placed directly on the cellular oor units before the concrete is placed on the floor. The crossover ducts extend in directions transverse of the ducts through the cellular floor units, and openings are provided through the bottoms of the crossover ducts and through the top walls of the cellular floor ducts for the passage of wires from one duct to another.

It is an object of this invention to provide an improved construction for crossover ducts at the regions where these ducts communicate with the cellular iloor ducts. The invention is particularly applicable to oversize crossover ducts which are designed for carrying more than the usual number of wires or conductors, and one object of the invention is to provide a greater cross section of opening between the crossover duct and the underlying duct of the cellular floor.

Another object of the invention is to provide a simple and inexpensive bottom wall construction for a crossover duct. One feature relates to a rolled-over edge around the opening through which the wires or conductors are pulled and the rolled-over edge is constructed in such a way as to provide a smooth surface contact around and across which the conductors can be pulled without danger of damaging the insulation of the conductors, even though the conditions are such that the conductors are subject to very substantial force in being pulled through the ducts and openings.

Other objects, features and advantages of the invention will appear or be pointed out as the description proceeds.

In the drawing, forming a part hereof, in which like reference characters indicate corresponding parts in all the views;

Figure l is a top plan view of a crossover duct embodying this invention;

Figures 2 and 3 are greatly enlarged sectional views taken on the lines 2 2 and 3-3, respectively, of Figure 1;

Figure 4 is a top plan View of a T fitting embodying the invention;

Figure 5 is a greatly enlarged sectional view taken on the line 5 5 of Figure 4; and

Fig. 6 is ary enlarged, fragmentary, sectional View showing the relation of the edges of the cell opening and the downturned edge of the crossover duct opening.

The crossover duct 9 shown in Figures l and 2 includes a top 10, side walls 11, and a bottom 12. These are preferably of one-piece construction, the duct being made by forming a single strip of metal. There is an opening 14 in the top wall 10 for providing access to the interior of the ducts. Above this opening 14, it is customary to place a neck fitting 16 which has its upper end ush with the iinal level of a concrete oor 18. The

neck fitting 16 is closed by a plate 20 threaded into the fitting 16, or by other suitable closing means.

In the bottom wall 12 there is an opening 22. In the conventional crossover duct, this opening in the bottom wall is circular, and concentricr with the opening 14 through the top wall, but in the present invention, the opening 22 is made much longer than usual, so as to provide a greater open cross section for the passage of wires into the duct, and the edges of the opening 22 are made differently from those of the conventional duct which merely has a knockout in the bottom wall.

The crossover duct 9 rests on a cell 26 of the cellular ilooring, and an opening 28 is provided in the cellular floor duct 26 at a location immediately below the opening 22 of the crossover duct. The metal edge portions around the opening 22 are bent downwardly and then outwardly so as to provide a rounded lip 30. The edge 32 of the metal which is bent downwardly and outwardly is preferably located just below the inside face of the cellular oor duct 26, and the total curvature of the bend is slightly more than a so that the metal adjacent to the edge 32 slopes upwardly at a slight angle to the top Wall of the duct 26. This angle, designated by the reference character 34, is preferably about 5 so that the edge 32 is spaced from a horizontal tangent to the curved surface 30.

This construction locates the edge face 32 out of the path of wires 36 which are pulled through the ducts. The structure can, therefore, be made by inexpensive manufacturing processes which leave a sharp, or even a slightly burred face at the edge 32.

The opening 22 is made at the time when the duct is manufactured, and the radial extent of the turned-over edge portion of metal around the opening is, therefore, kept small so that it can pass through the opening 28 in the cellular oor duct without obstructing any more than necessary of the open cross section of the opening 28. Figure 6 shows the positions of the edges of the opening 22 and opening 28 with respect to one another when the parts are in their assembled relation.

The vertical extent of the bent edge portion, around the opening 22, is kept small so that standard sections of the crossover duct can pass across portions of a cellular licor in which it is unnecessary to provide an opening; and the contact of the downwardly and outwardly bent portions of metal around the opening 22 is not suicient to raise appreciaibly the level of the crossover duct with respect to the cellular flooring.

The additional size of the opening 22, as compared with ducts having circular knockouts, is obtained by increasing the dimension of the opening in the direction in which the duct extends. This is advantageous because the vertical height of the crossover duct is substantially less than that of the cellular floor ducts and the elongated opening 22 provides space for the gradual downward bend of a group of conductors which may be more tightly packed in the crossover duct than in the cellular floor duct which is of much greater height and cross section.

Figure 4 shows the invention applied to a cross fitting 40. This iitting has four outlets and has a large circular opening 42 in its top wall. ln the bottom wall of the fitting 40, there is an opening 22 corresponding to the opening 22 in the bottom wall of the duct shown in the previous figures.

Figure 5 shows the way in which the fitting 4@ is assembled with a cellular floor duct 26. The edges around the opening 22 are the same as with the corresponding opening of the duct 9 of Figures l and 2. The tting 40 has stops 45 for limiting the extent to which a section of duct can be inserted into thc fitting. The opening 22 extends 3, in a direction in line with the ducts which connect with the itting 4t).

The preferred embodiments of the invention have been illustrated and described but changes and modications can be made, and some features of the invention can -be used in different combinations without departing from the invention as defined in the claims.

I claim as my invention:

1. The combination, with a cellular floor duct having an opening in its top wall, of an electric wiring duct l0- cated on top of the cellular oor duct and extending longitudinally in a direction transverse of the direction in which the cellular loor duct extends and in a plane generally parallel to the direction of the cellular oor duct, said wiring duct having a top wall with an opening therein and a bottom wall having an opening therethrough for access to the interior of the cellular floor duct, the bottom wall having portions surrounding the opening therethrough, said portions extending downwardly through the opening in the top wall of the cellular oor duct for a distance greater than the thickness of the top wall of the iioor duct and then extending outwardly to form a peripheral groove around the downwardly extending portions and `between the bottom of the duct and the outwardly extending portions, the maximum dimensions across said outwardly extending portion of the bottom wall being less than the corresponding dimensions ot the opening through the top wall of the floor duct.

2. The combination described in claim 1 and in which said outwardly extending portions of the bottom wall have an upward curve that is tangent at its outer limits to a cone which makes an acute angle with the bottom wall ot' the electric wiring duct of about 5 to 15 degrees.

3. An article of manufacture consisting of awiring duct which is to be assembled with a cellular oor and which has a longitudinally extending passage therein for electric wiring, and a generally at top wall with an opening therein, the axis of the opening extending transversely of the longitudinal extent of the passage, and the duct having also a bottom wall with an opening therethrough l0- cated directly under the top opening and substantially in line therewith, said duct, before assembly with the cellular floor or any other structure, having portions of the bottom surrounding the opening in the bottom wall, which por tions extend downwardly below the bottom of the duct for a distance greater than the thickness of the material of the bottom wall and then outwardly at their lower ends to form a peripheral groove around the downwardly extending portions and between the bottom of the wiring duct and the outwardly extending lower ends of said p0rtions.

4. The duct described in claim 3 and in which the downturned and outwardly extending portions curve upwardly toward their periphery to a final direction at a small acute angle to the longitudinal direction of extent of the bottom wall of the duct.

References Cited in the le of this patent UNITED STATES PATENTS 1,824,571 Richardson Sept. 22, 1931 2,125,366 Young et al. Aug. 2, 1938 2,149,060 Mackey Feb. 28, 1939 2,161,492 Wadsworth June 6, 1939 2,297,179 Walker Sept. 29, 1942 2,445,197 Weismann July 13, 1948 2,511,277 Lumley June 13, 1950 2,672,749 Weismann Mar. 23, 1954 

